The present disclosure relates to couplings made from a spinodally-hardened copper alloy. The couplings are particularly useful for connecting sucker rods to affect a connection between a power source and a pump, and may also be useful for other couplings used in the oil and gas industry, such as a polished rod coupling or a subcoupling.
Hydrocarbon extraction apparatuses typically include a pump for extracting hydrocarbons from an underground reservoir, a power source for providing power to the pump, and a sucker rod lift system connecting the power source and the pump. The sucker rod lift system includes a series of sucker rods that are joined together by couplings. The sucker rods and couplings are joined by a pin-and-box threaded connection. Damage to threaded connections due to galling (wear due to adhesion between sliding surfaces) can compromise the mechanical integrity of the joint and lead to failure of the connection between the power source and the pump. In addition, the sucker rod lift system operates within a conduit. Damage to the conduit caused by repetitive contact between the outer surface of the coupling and the inner surface of the conduit can compromise the mechanical integrity of the conduit, leading to leakage of the hydrocarbons carried by the conduit into the environment. Such leakage effectively stops the pumping process and often leads to very costly additional operations to remediate such failures.
Desired characteristics of sucker rod couplings and similar couplings include high tensile strength, high fatigue strength, high fracture toughness, galling resistance, and corrosion resistance. Conventional couplings are typically comprised of steel or nickel alloys which lack the full complement of preferred intrinsic characteristics, particularly galling resistance. Expensive surface treatments are typically used to increase galling resistance on couplings made from steel or nickel alloys, as well as on the inside of the conduit inside which the coupling is disposed. These surface treatments eventually wear off, and must be re-applied periodically over the course of the lifetime of the parts in order to be effective.
It would be desirable to develop new sucker rod couplings having improved intrinsic galling resistance as well as other desirable properties.